RF-front-end for a radar system

ABSTRACT

An RF sender/receiver front-end is disclosed comprising a terminal for receiving an oscillator signal, at least one distribution unit for distributing the oscillator signal into different signal paths, two or more mixer-arrangements for sending a transmit-signal or for receiving an receive-signal, where each mixer-arrangement comprises a mixer and an amplifier for amplifying the oscillator signal and generating the transmit-signal.

This application is a divisional of U.S. patent application Ser. No.11/803,343, filed May 14, 2007, which is incorporated herein byreference.

TECHNICAL FIELD

The invention relates to a radio frequency sender/receiver front-end fora radar system.

BACKGROUND

Known radar systems which are currently used for distance measurement invehicles essentially comprise two separate radars which operate indifferent frequency bands. For distance measurements in a near area(short range radar), radars which operate in a frequency band around amid-frequency of 24 GHz are commonly used. In this case, the expression“near area” means distances in the range from 0 to about 20 meters fromthe vehicle (short range radar). The frequency band from 76 GHz to 77GHz is currently used for distance measurements in the “far area”, thatis for measurements in the range from about 20 meters to around 200meters (long range radar). These different frequency bands areantithetical to the concept of one single radar system for bothmeasurement areas and often require two separate radar devices.

The frequency band from 77 GHz to 81 GHz is likewise suitable for shortrange radar applications. A single multirange radar system which carriesout distance measurements in the near area and far area using a singleradio-frequency transmission module (RF front-end) has, however, not yetbeen feasible for various reasons. One reason is that circuits which aremanufactured using III/V semiconductor technologies (for examplegallium-arsenide technologies) are used at the moment to construct knownradar systems. Gallium-arsenide technologies are admittedly highlysuitable for the integration of radio-frequency components, but it isnot possible to achieve a degree of integration which is as high, forexample, of 5 that which would be possible with silicon integration, asa result of technological restrictions. Furthermore, only a portion ofthe required electronics are manufactured using GaAs technology, so thata large number of different components are required to construct theoverall system.

However, a high number of components is not desirable, since losses andreflections arise in each component, especially in the signal pathdownstream to the RF power amplifier. These losses and reflections havean undesired negative impact on the efficiency of the overall system.Thus there is a general need for a RF sender/receiver front-end whichprovides for high flexibility at high integration level and highefficiency.

SUMMARY

The RF sender/receiver frontend according to one example of theinvention comprises a terminal for receiving an oscillator signal, atleast one distribution unit for distributing the oscillator signal intodifferent signal paths, two or more mixer-arrangements for sending atransmit-signal or for receiving an receive-signal, where eachmixer-arrangement comprises a mixer and an amplifier for amplifying theoscillator signal and generating the transmit-signal.

One aspect of at least some embodiments of the invention relates to amixer-arrangement. An exemplary embodiment of the mixer-arrangementcomprises an oscillator terminal for receiving an oscillator signal, anRF terminal for connecting an antenna, a base-band terminal forproviding a base-band signal, a mixer having a first input which isconnected to the oscillator terminal, a second input, and an outputwhich is connected with the base-band terminal, a directional couplerwhich is connected with the oscillator-terminal and the RF terminal forcoupling the oscillator signal to the antenna and for coupling a signalreceived from the antenna to the second input of the mixer, and adisconnecting device for interrupting the signal.

The amplifier of the sender/receiver front-end may be able to be enabledand disabled by a control signal. In this case the amplifier may alsoserve as the disconnecting device of the mixer arrangement.

With the help of the mixer arrangement the RF sender/receiver front-endmay be configured to operate either in a pure receive-mode or in acombined send-and-receive-mode of an antenna which is connected to theRF front-end.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention can be better understood with reference to the followingdrawings and description. The components in the figures are notnecessarily to scale, instead emphasis being placed upon illustratingthe principles of the invention. Moreover, in the figures, likereference numerals designate corresponding parts. In the drawings:

FIG. 1 shows a radar system in which the same antenna is used forlong-range and short-range measurements,

FIG. 2 shows a radar system with different antennas for long-range andshort-range measurements,

FIG. 3 shows a more detailed illustration of the system shown in FIG. 2,

FIG. 4 shows a more detailed illustration of the system illustrated inFIG. 3,

FIG. 5 shows an alternative to the system illustrated in FIG. 4,

FIG. 6 shows the internal design of the transmission oscillator in theform of a block diagram,

FIG. 7A shows a mixer-arrangement for mixing a RF receive-signal intothe base-band,

FIG. 7B shows a mixer-arrangement for a combined send-and-receive-modeof operation of a connected antenna,

FIG. 8A shows a mixer-arrangement which is configured to a combinedsend-and-receive mode of operation, the mixer-arrangement beingconfigurable by a control signal and comprising an amplifier which canbe enabled and disabled by the control signal,

FIG. 8B shows a mixer-arrangement which is configured to a pure receivemode of operation, the mixer-arrangement being configurable by a controlsignal and comprising an amplifier which can be enabled and disabled bythe control signal,

FIG. 9A shows a mixer-arrangement which is configurable by laser fuses,

FIG. 9B shows a mixer-arrangement which is configurable by laser fuses,the mixer-arrangement being configured to a pure receive mode ofoperation,

FIG. 9C shows a mixer-arrangement which is configurable by laser fuses,the mixer-arrangement being configured to a combined send-and-receivemode of operation,

FIG. 10 shows one example of the switchable amplifier of FIG. 8A or 8B,and

FIG. 11 shows one example of the inventive RF sender/receiver front-endcomprising the configurable mixer of FIG. 8A or 8B.

FIG. 12 a shows a cross-section of an example of the invention, whereRF-front-end of FIG. 11 and an antenna are arranged in one commonpackage.

FIG. 12 b shows a bottom-view of the arrangement of FIG. 12 a.

DETAILED DESCRIPTION

FIG. 1 uses a block diagram to show the basic structure of one exampleof a radar system. The actual multirange radar MRR has a control andprocessing unit 110 which is connected to the other vehicle components100 via a specific interface, for example the vehicle bus. Themultirange radar MRR also comprises a radio-frequency (RF) transmissionmodule 120 and an antenna module 130 which comprises one or moreindividual antennas. The control and processing unit 110 may be designedpredominantly using CMOS technology, whereas the RF transmission module120 may be designed predominantly using bipolar technology. However, itis also possible to integrate both parts jointly using BiCMOStechnology. The multirange radar comprises at least two rangemeasurement zones, a near area for ranges between 0 and about 20 meters(short-range radar), and a far area with ranges from around 20 meters toabout 200 meters (long-range radar). Since both the transmission andreception characteristics of the active antennas as well as the requiredbandwidth of the transmitted radar signal are different in these twomeasurement ranges, both the antenna module 130 and the radio-frequencytransmission module 120 can be configured by means of control signalsCF0 and CF1, which are provided by the control and processing unit 110,in accordance with the desired measurement range. The details of thisconfiguration capability will be explained in more detail further below.

An antenna with a fairly broad emission angle is desirable for ameasurement in the short range and an antenna with a narrow emissionangle and a high antenna gain is desirable for measurement in the longrange. For this reason, phased-array antennas may be used, by way ofexample, in the antenna module 130, whose transmission reception anglecan be varied by driving different antenna elements with the sameantenna signal, but with a different phase angle of the antenna signal.Variation of the transmission and reception characteristics of antennasby means of an appropriate driver is also referred to as electronicbeam-control or digital beam-forming.

The RF transmission module 120 also comprises the radio-frequencyfront-end which is required for the reception of the reflected radarsignals. The received radar signals are mixed to baseband with the aidof a mixer, the baseband signal IF is then supplied from theradio-frequency transmission module 120 to the control and processingunit 110, which digitizes the baseband signal IF and processes itfurther by digital signal processing. It is not only possible to providea separate transmitting antenna and receiving antenna (bistatic radar),but also a common antenna for transmission and reception of radarsignals (monostatic radar). In the second case, a directional coupler isrequired to separate the transmitted signals and the received signals.The internal design of the RF transmission module 120 and of the antennamodules 130 will likewise be described in more detail later.

Electronic beam control (digital beam-forming) allows a minimal numberof components, but requires considerably greater control logiccomplexity. For this reason, different antennas 130 a and 130 b may beused for the different measurement ranges, as is shown in the exampleillustrated in FIG. 2. The block diagram in FIG. 2 differs from that inFIG. 1 only in that two antenna modules 130 a and 130 b are providedinstead of the antenna module 130 which can be configured via thecontrol signal CF1, and their emission and reception characteristics arenot adjustable. For example, the antenna 130 a is designed only formeasurements in the short range, and the antenna 130 b is designed onlyfor measurements in the long range. However, the transmission signalsare generated and the received signals are mixed in a commonradio-frequency sender/receiver front-end 120. In principle, when usingtwo antennas, it is also possible to simultaneously carry outmeasurements in the short range and in the long range (frequencymultiplexing mode) instead of alternate measurement (time multiplexingmode).

FIG. 3 shows essentially the same example as illustrated in FIG. 2, butwith the control and processing unit 110 and the RF sender/receiverfront-end 120 being illustrated in more detail. The control andprocessing unit 110 comprises a computation unit 111, a digital/analogconverter 114, an analog/digital converter 113 with an upstreamdistribution block 112 which, for example, may be in the form of amultiplexer. The RF sender/receiver front-end 120 comprises aradio-frequency oscillator 121, which produces the transmission signal,a distribution unit 122 which distributes the signal power, depending onthe operating mode, to a first transmitting/receiving circuit 123 a orto a second transmitting/receiving circuit 123 b (time multiplexingmode), or else between both transmitting/receiving circuits 123 a and123 b (frequency multiplexing mode).

As already mentioned, the multirange radar comprises a first operatingmode for measurement of distances in the short range, and a secondoperating mode for measurement of distances in the long range. Theoperating mode is elected by the computation unit 111 by providing theappropriate control signals CT0, CT1 and CT2. The control signals CT1and CT2 respectively activate and deactivate the respectivetransmitting/receiving circuits 123A and 123B, and the control signalCT0 configures the distribution unit 122 in accordance with the desiredoperating mode. The computation unit 111 additionally provides a digitalreference signal REF, which is supplied to the oscillator 121 via adigital/analog converter 114. This reference signal REF governs theoscillation frequency of the output signal OSZ of the oscillator 121,which is supplied to the distribution unit 122. For a measurement in theshort range, the distribution unit 122 is configured in such a mannerthat the transmission signal is supplied only to thetransmitting/receiving circuit 123 a, which is activated by the controlsignal CT1. The second transmitting/receiving circuit 123 b isdeactivated by the control signal CT2. The transmitting/receivingcircuits 123 a and 123 b essentially also comprise a transmissionamplifier output stage via which the transmission signal is supplied tothe respective antenna modules 1230 a and 130 b.

In addition, the transmitting/receiving circuit 123 a contains one ormore mixers with the aid of which the radar signals which are receivedby the receiving antennas are mixed to baseband. The baseband signal IF1is then made available by the transmitting/receiving circuit 123 a tothe distributor block 112 in the control and processing unit 110.Depending on the number of receiving antennas, the baseband signal IF1comprises a plurality of signal elements. The baseband signal IF1 isdistributed by the distributor block 112 to an analog/digital converter113, which has one or more channels, and is made available from thisanalog/digital converter 113 in digital form to the computation unit111. This computation unit 111 can then use the digitized basebandsignals IF1 to identify objects in the “field of view” of the radar, andto calculate the distance between them and the radar. This data is thenmade available via an interface, for example a vehicle bus BS, to therest of the vehicle.

For a measurement in the long range, all that is necessary is switchingin the distributor unit 122, activation of the transmitting/receivingcircuit 123 b and deactivation of the transmitting/receiving circuit 123a by means of the control signals CT0, CT1 and CT2. The transmission andreception then take place via the antennas 130 b, which in the presentcase are in the form of common transmitting and receiving antennas. Forthis reason, a directional coupler is also required to separate thetransmission signal and the received signal. What has been said for thefirst transmitting/receiving circuit 123 a also, of course, appliesanalogously to the second transmitting/receiving circuit 123 b. Thedetailed design of the transmitting/receiving circuits 123 a and 123 bwill be explained with reference to a further figure.

The transmitting/receiving circuits 123 a and 123 b can be deactivatedin various ways. In the simplest case, the circuits (or else onlycircuit elements) are disconnected from the supply voltage. It is alsopossible to switch off the mixers in the transmitting/receivingcircuits. Irrespective of the specific manner in which the deactivationis accomplished, it is, however, necessary to ensure that the power ofthe transmission signal is not reflected, and therefore does notinterfere with any other circuit components.

FIG. 4 essentially shows the example of FIG. 3, with the computationunit 111, the distributor block 122 and the transmitting/receivingcircuits 123 a and 123 b being illustrated in more detail. Thetransmitting/receiving circuits 123 a and 123 b each comprise anamplifier 126 to which the transmission signal is supplied. Theseamplifiers 126 have a plurality of outputs, at least one of which isconnected to a transmitting antenna, and at least a second of which isconnected to a mixer 127. If disturbance or interference signals whichhave to be filtered out are present, a filter 125 may be in each casearranged between the amplifier 126 and the transmitting antenna, andbetween the amplifier 126 and the mixer 127. In thetransmitting/receiving circuit 123 a, the mixers 127 are connected notonly to the amplifier 126 but also to the receiving antenna, so that thereceived signal is mixed to baseband by the mixer 127 with the aid ofthe transmission signal.

In the illustrated example, one transmitting antenna and two receivingantennas are provided in the antenna module 130 a. This should beregarded only by way of example, and in principle any desiredcombination of transmitting and receiving antennas is possible. Insteadof separate transmitting and receiving antennas, it would also bepossible to use bidirectional antennas, as is the case with the antennamodule 130 b.

The transmitting/receiving circuit 123 b differs from thetransmitting/receiving circuit 123 a described above by comprising thedirectional couplers 128 which allow the antennas in the antenna module138 to be used both as transmitting antennas and as receiving antennas.The directional couplers 128 have four connections, of which a firstconnection is connected to the amplifier 126, a second connection isconnected to a terminating impedance, a third connection is connected toa mixer 127 and a fourth connection is connected to one antenna of theantenna module 130 b. The transmission signal is passed from theamplifier 126 through the directional coupler to the antenna, where thesignal power is emitted from. A received signal is passed from theantenna through the directional coupler to the mixer 127, where it ismixed to baseband with the aid of the transmission signal, which islikewise supplied to the mixer 127. The output signals from the mixers,i.e. the baseband signals IF0, IF1 are then multiplexed by thedistributor block 112, and are digitized by the analog/digital converter113. These digitized signals are buffered in a FIFO memory 119 and areprocessed further by a digital signal processor 118. The FIFO memory 119and the digital signal processor 118 are components of the computationunit 111, as is the clock generator 117, which provides a clock signalfor the digital signal processor 112 and for the analog/digitalconverter 113. The control logic 116 provides the control signals CT0,CT1 and CT2 and likewise controls a reference signal generator 115,which produces the digital reference signal REF for the oscillator 121(see above).

The distribution unit 122, which distributes the oscillator signal OSZto the transmitting/receiving circuits 123 a and 123 b, has only oneswitch SW in the illustrated situation, which may, for example, be inthe form of a semiconductor switch or a micromechanical switch. Thisswitch connects the oscillator 121 either to the firsttransmitting/receiving circuit 123 a or to the secondtransmitting/receiving circuit 123 b. Filters 125 are likewise arrangedbetween the switch SW and the transmitting/receiving circuits 123 a, 123b, provided that disturbing signals are present. It is also possible toconnect the oscillator directly to the two transmitting/receivingcircuits 123 a and 123 b (that is to say without the provision of aswitch SW), or to provide a passive power splitter. The oscillator poweris then split between the two transmitting/receiving circuits. Asalready mentioned, it is important in this case to prevent reflectionswhen one of the transmitting/receiving circuits 123 a, 123 b isdeactivated. Suitable terminating impedances must therefore be providedat an appropriate circuit node.

The example illustrated in FIG. 4 is designed for a so-called timemultiplexing mode, i.e. switching takes place alternately from the firstoperating mode to the second operating mode, and back again. Thefrequency ranges for measurements in the near area in the firstoperating mode and for measurements in the far area in the secondoperating mode may in this case in principle overlap, since only one ofthe two antenna modules 130 a or 130 b is ever active.

FIG. 5 shows a very similar exemplary embodiment which operates usingthe frequency multiplexing mode. This differs from the exemplaryembodiment shown in FIG. 4 only by having a modified distributor unit122, the additional reference signal generator 115′ with the additionaldigital/analog converter 114′. Since measurements are carried outsimultaneously in the near area and in the far area in thefrequency-division multiplexing mode, the multiplexer 112 may not berequired in this case, but the analog/digital converters 113 would thenhave to comprise a plurality of channels in order to allow the receivedsignals, which have been mixed to baseband, to be digitized in parallel.

In the example of FIG. 5, instead of a switch, the distributor unit 122has an additional mixer 127 and an additional oscillator 129. The outputsignal OSZ from the oscillator 121 is on the one hand supplied to themixer 127 in the distributor unit 122, and is on the other hand passedon via an optional filter 125 to the transmitting/receiving circuit 123b as well. The spectrum of the signal component of the oscillator signalOSZ supplied to the mixer 127 is frequency shifted by the oscillatorfrequency of the auxiliary oscillator 129, and is supplied via a filter125 to the transmitting/receiving circuit 123 a. The auxiliaryoscillator 129 is likewise controlled by the computation unit 111 withthe aid of the reference signal generator 115′ and the digital/analogconverter 114′, which is connected to it and whose output signal issupplied to the auxiliary oscillator 129. The mixer 127 and theauxiliary oscillator 129 thus result in the production of a second,frequency-shifted transmission signal, so that the twotransmitting/receiving circuits 123 a can transmit and receive at thesame at different frequencies via the two antenna modules 130 a and 130b, respectively. This allows simultaneous measurement in the near areaand in the far area.

FIG. 6 shows one possible configuration of the radio-frequencyoscillator 121, with whose aid the transmission signal is produced. Thisessentially comprises a phase locked loop (PLL) to which the analogreference signal REF′ which is produced by the digital/analog converter114 is supplied. The major element of the phase locked loop is avoltage-controlled radio-frequency oscillator 143 whose output signal issupplied on the one hand to a frequency divider 145, and on the otherhand to a filter 125. The output signal from the filter 125 representsthe output signal OSZ from the phase-locked loop. The output signal fromthe frequency divider 145 is supplied to a mixer 127 which uses anauxiliary oscillator 144 to shift the spectrum of the frequency-dividedoscillator signal by the magnitude of the frequency of the auxiliaryoscillator 144 towards a lower value. The output signal from the mixeris divided down once again by a further frequency divider 146.

The output signal from this further frequency divider 146 thusrepresents the oscillator signal of the radio-frequency oscillator 143,which is compared with the previously mentioned reference signal REF′with the aid of the phase/frequency detector 141. This phase/frequencydetector 141 produces a control voltage as a function of the frequencyand phase difference between the output signal from the frequencydivider 146 and the reference signal REF′. This control voltage issupplied to a loop filter 142, whose output is connected directly to thevoltage-controlled radio-frequency oscillator 143. Thevoltage-controlled radio-frequency oscillator 143 is thus dependent onthe phase difference and/or frequency difference between the outputsignal from the frequency divider 146, which represents the oscillatorsignal, and the reference signal REF′. The phase and the frequency ofthe output signal OSZ from the phase locked loop thus have a fixedrelationship with the phase and the frequency of the reference signalREF′. The voltage-controlled radio-frequency oscillator 143 must betunable over a broad frequency range, in the present case in the rangefrom 76 GHz to 81 GHz, that is to say over a bandwidth of 5 GHz. Sincethe mid-frequency can also be shifted by temperature effects and otherparasitic effects, a bandwidth of 8 GHz or more is required in practice,and this can be achieved only by using the modern bipolar or BiCMOStechnology that has already been mentioned further above.

As it can be seen in FIGS. 3 to 5 the antennas 130, 130 a and 130 b mayeither configured to be used as receiving antennas, as transmittingantennas, or as common transmitting/receiving antennas. With“transmitting-only” antennas the transmitting signal TX is generatedfrom the oscillator signal OSZ of the voltage control oscillator byamplification, and the transmitting signal TX is supplied to theantenna. With the “receiving-only” antenna a mixer 127 is needed forreceiving, the mixer is adapted for mixing a received signal RX intobaseband and for providing the respective baseband signal IF. With acommon transmitting/receiving antenna a directional coupler 128 isnecessary for separating the received signal RX from the transmittingsignal TX. The antennas—dependent on the application—may be arrangedtogether with the RF front on one common lead frame in one commonchip-package. FIGS. 12 a and 12 b refer to such an example.

As it can be seen from the example of FIG. 4 or 5, the oscillator signalOSZ in the transmitting/receiving circuit 123 b (123 a respectively) isamplified for providing the necessary signal power. The amplified RFoscillator signal is than supplied to the antennas and the mixers,wherein at each component (splitter, coupler, mixer, etc.) reflectionsand losses occur, which has a negative impact on the efficiency of theoverall system.

Several different mixer arrangements 300 each comprising a directionalcoupler 128 and a mixer 127 are illustrated in FIG. 7 to 9. Such mixerarrangements 300 may be used, for example for designing atransmitting/receiving circuit similar to circuit 123 b. Each of thesemix arrangements 300 comprises an RF terminal 301, an oscillatorterminal 302, and a baseband terminal 303. The oscillator signal OSZ (oralternatively an amplified oscillator signal) is supplied to theoscillator terminal 302; the RF terminal is connected to the antenna,which either emits a transmitting signal TX and/or receives an receivingsignal RX. At the baseband terminal 303 a baseband signal IF is providedfor further processing, wherein the baseband signal IF is generated bymixing the received signal RX and the oscillator signal OSZ. Atransmitting/receiving circuit comprising such mixer arrangements 300 isdepicted in FIG. 11 and labeled with the reference sign 123 c. Thetransmitting/receiving circuit 123 c may replace thetransmitting/receiving circuits 123 a or 123 b of FIGS. 3 or 4 forimproving the efficiency of the overall system.

The mixer arrangement depicted in FIG. 7 a comprises a mixer 127 as itsessential component. A first input of the mixer 127 is connected withthe oscillator terminal 302 of the mixer arrangement 300, the oscillatorsignal of the voltage controlled oscillator being supplied to theoscillator terminal 302. A second input of the mixer 127 is connectedwith the RF-terminal 301, the received signal RX of the antenna beingsupplied to the RF-terminal 301. An output of the mixer 127 is connectedwith the baseband terminal 303 thus providing a baseband signal IF. Themixer arrangement described above obviously only can be employed forreceiving; it is not possible to transmit signals.

If the antenna is supposed to be used as a common transmitting/receivingantenna, a directional coupler 128 has to be provided as depicted inFIG. 7 b. The mixer arrangement 300 of FIG. 7 b comprises an directionalcoupler 128 and a mixer 127 as its essential components. The oscillatorsignal is supplied to the oscillator terminal 302 of the mixerarrangement 300; the oscillator terminal 302 is connected with a firstterminal of the directional coupler 128.

The oscillator signal OSZ is coupled by the directional coupler 128 toboth the antenna as well as the mixer 127 as indicated by the arrows inFIG. 7 b. The directional coupler 128 thus couples the oscillator signalOSZ incident at its first terminal to a fourth terminal of thedirectional coupler 128 and to a second terminal of the directionalcoupler 128. The fourth terminal is connected to the RF-terminal 301 andtherefore to the antenna 130. The second terminal is connected with thefirst input of the mixer 127.

A received antenna signal RX arrives at the fourth terminal of thedirectional coupler 128 via the RF terminal 301 and is coupled by thedirectional coupler 128 to the mixer 127 via the third terminal of thedirectional coupler 128. The mixer 127 generates the baseband signal IFfrom the received antenna signal RX and the oscillator signal OSZ andprovides the baseband signal IF at the base-band terminal 303 forfurther processing.

If the antenna configuration is to be varied or different applicationsrequire different system architectures (and therefore a differentantenna- and mixer-configuration), then it is desirable, that thesedifferent mixer configurations do not require different hardwaresolutions, and that one mixer-hardware is configurable for a differentapplications. FIGS. 8 a and 8 b illustrate a mixer arrangement which isconfigurable (by switching) for a “receiving only” mode and a commontransmitting/receiving mode. FIG. 8 a illustrates the configuration andthe signal flow for the common transmitting/receiving mode and FIG. 8 bfor the receiving-only mode.

The configurable mixer arrangement 300 of FIGS. 8 a and 8 b comprises adirectional coupler 128, a mixer 127, a terminating impedance R, and aswitchable, respectively configurable amplifier 310. Analogues to themixer arrangements of FIGS. 7 a and 7 b the mixer arrangements 300 ofFIGS. 8 a and 8 b comprise an RF-terminal 301, an oscillator terminal302, and a baseband terminal 303. The RF-terminal 301 is connected withboth the antenna and the fourth terminal of the directional coupler. Theoscillator terminal 302 is connected with both the input of theamplifier 310 and the first input of the mixer 127, such that theoscillator signal OSZ, which is received by the oscillator terminal 302,is coupled to the mixer 127 as well as to the amplifier 310. Thebaseband terminal 303 is connected to the output of the mixer.

The output of the amplifier 310 is connected with the first terminal ofthe directional coupler 128. In the example of FIG. 8 the amplifier 310can be enabled (Spa=on) and disabled (Spa=off) by a control signal Spa.The control signal Spa can assume two logic levels (on or off),according to which the amplifier is either activated or deactivated.With an activated amplifier 310 the oscillator signal is amplified andcoupled to the fourth terminal of the directional coupler 128 andemitted as transmitting signal TX via the antenna. A part of the powerof the oscillator signal is coupled to the terminating impedance R viathe second terminal of the directional coupler 128. This terminatingimpedance R has to be chosen, such that no signal power is reflected.

The received signal RX received by the antenna is coupled via thedirectional coupler 128 (as indicated by the arrows) to the second inputof the mixer 127, where the received signal RX is mixed with theoscillator signal OSZ for providing a base-band signal IF. A part of thesignal power of the received signal RX is coupled via the directionalcoupler 128 to the output of the amplifier 310. The received signal RXhas to be terminated at the amplifier output by means of a suitableterminating impedance for inhibiting undesired reflections.

FIG. 8 b illustrates the case where the mixer arrangement 300 isconfigured as receiving-only mixer. Therefore, the amplifier 310 isdeactivated by a corresponding level (Spa=off) of the control signal Spaand no transmitting signal is coupled to the antenna. The receivedsignal RX is processed analogue to the case shown in FIG. 8 a.

The mixer arrangements depicted in FIGS. 8 a and 8 b allow for aconfiguration of the operating mode of the mixer arrangement by acontrol signal Spa, the operating mode can be either the combinedsending/receiving mode, or the receiving-only mode. Consequently, thesame hardware component can be used with different systemconfigurations. This is especially useful for chips comprising aplurality of mixer arrangements which are employed in different systemconfigurations.

The example illustrated in FIGS. 9 a, 9 b and 9 c does not allow arepeatable configuration of the mixer arrangement 300 by means of acontrol signal, but only a configuration being performed once by fusinglaser fuses 350 to 355, or by depositing an optional (maybe final)metallisation layer thus providing the last missing electricalconnections. FIG. 9 a illustrates the initial configuration, startingfrom which the arrangement of FIG. 9 b or the arrangement of FIG. 9 c isproduced. The arrangement of FIG. 9 b corresponds to the arrangement ofFIG. 7 a, the arrangement of FIG. 9 c corresponds to the arrangement ofFIG. 7 b.

In order to get a receiving-only mixer (cf. FIG. 7 a or FIG. 9 b) fromthe initial configuration, the fuses 350, 352, 353, and 355 have to befused, for example by a laser-beam during the production process. Inorder to get a combined transmitting/receiving mixer (cf. FIG. 7 b orFIG. 9 c), the fuses 351 and 354 have to be fused.

Instead of laser fuses 350 to 355 intermittent signal paths in themetallization layer can be used. At the places, where in the casedescribed above the fuses are not fused, the interruptions of the signalpaths are closed by disposing a further metallization at the place ofthe interruptions in the signal paths (e. g. strip lines).

FIG. 10 illustrates an example of an amplifier which can be activated ordeactivated by a control signal Spa. The oscillator signal OSZ and thetransmitting signal TX are differential signals, i. e. signals which arenot ground related, in the example of FIG. 10. The oscillator signal OSZis supplied to two corresponding terminals as indicated by the arrow.The first stage 311 of the amplifier is an emitter follower, whoseoutput signal is again amplified by the differential amplifier 313. Thecurrent mirror 314 thereby serves as current source for the differentialamplifier 313. By switching of the current source the amplifier may bedeactivated. In order to do so, for example a switch may be providedwhich switches off the current in the reference path of the currentmirror 314. The output signal (transmitting signal TX) is provided atthe two corresponding output terminals as a symmetric differentialsignal.

FIG. 11 depicts, as one example of the invention, a sender/receiverfront-end 120, which has to be understood as a possible alternative orsupplement to the sender/receiver front-ends 120 depicted in FIGS. 3 to5. The transmitting/receiving circuits 123 a and 123 b of FIGS. 4 and 5may be replaced by the sending/receiving circuit 123 c of FIG. 11, whichessentially provide the same function. The sender/receiver front-end 120of FIG. 11 may comprise an RF-oscillator (e. g. a voltage controlledlocal oscillator) which provides an oscillating signal OSZ depending onthe analog reference signal REF′ (cf. FIG. 4). The oscillator signal OSZis supplied to the distribution unit 122 which distributes the singlepower, dependent on the mode of operation, to the connectedtransmitting/receiving circuit. In the present case only onetransmitting/receiving circuit 123 c is depicted for the sake ofsimplicity and clarity. Of course two or more transmitting/receivingcircuits can be connected to the distribution unit 122 (cf. FIGS. 3 to5).

The transmitting/receiving circuit 123 c comprises an optional filter125, whose output is connected to one or more of the mixer arrangements300 described with reference to FIGS. 8 a and 8 b. Instead of the(multi-output) filter 125 a further distribution unit (RF-splitter) or asimple parallel connection of the mixer arrangements 300 may be used asalternatives. The mixer arrangement is connected with one or moreantennas 130 and provides the baseband signals IF0, IF1 by mixing thereceived signals RX with the oscillator signal OSZ.

One important difference between the present example and the exampleillustrated in FIGS. 4 and 5 is, that the RF-transmitting signal is notonce “centrally” amplified before being distributed to the differentsignal paths each corresponding to an antenna (as performed, forexample, by the circuit 123 b of FIG. 4), but the amplification isperformed “locally” in each mixer arrangement 300 after the distributionof the un-amplified (low power) RF-transmitting signal. This entails aremarkable improvement of the efficiency of the overall RF front-end 120and an improvement of flexibility. Only un-amplified RF signals aredistributed to different signal paths and since the amplification isperformed in each signal path closely to the antenna, the losses in thesplitters, mixers, couplers, etc. are remarkably reduced. Since themixer arrangements 300 are configurable via a control signal Spa (whichmay depend or may be deducted from the control signal CT3), the overallsystem is also improved in terms of scalability. For example, even theantennas can be arranged together with the whole RF front-end on onecommon lead frame of one common chip package.

If a plurality of such chips are arranged on a PCB-board in a defineddistance, a phased-array for digital beam-forming can be easilyimplemented due to the flexible configurability of the RF front-end.

FIGS. 12 a and 12 b illustrate the common arrangement of RFsender/receiver front-end 120 and one or more antennas on one commonwafer 503 and on one common lead frame 500. The pads 501 connecting thepins of a chip package are connected to the silicon wafer 503 (and withthe RF front-end integrated therein) via bond wires 502. Additionally tothe RF front-end 120 one or more transmitting and/or receiving antennasare arranged on the wafer 503. In the present example only one antennais shown for the sake of simplicity and clarity.

Between antenna 130 and silicon wafer 503 a dielectric layer 510, forexample a silicon-oxide-layer and/or a silicon-nitride-layer, isarranged. The antenna 130 may be designed as folder deep hole antenna,as patch-antenna, as leaky-wave antenna, etc.

For providing a sufficient emission of radiation from the antenna acavity 540 b can be etched into the silicon layer below the antenna 130.If the radiation should be emitted in the direction towards the leadframe 500, also the lead frame 500 may have a cavity 504 a below theantenna. The antenna is then located on a thin membrane comprising thedielectric layer 510 and optionally a thin residual of the silicon layer503.

1. An RF sender/receiver front-end comprising: a terminal for receivingan oscillator signal, at least one distribution unit configured todistribute the oscillator signal into different signal paths, two ormore mixer arrangements configured to send a transmit-signal or toreceiving an receive-signal, at least one of said mixer arrangementsconfigured to transmit a transmit-signal and receive a receive-signaleach mixer arrangement operably coupled to receive the oscillatorsignal, each mixer arrangement comprising a mixer and an amplifierconfigured to amplify the oscillator signal and generate thetransmit-signal, wherein the amplifier is controllably enabled when anddisabled.
 2. The RF sender/receiver front-end of claim 1, furthercomprising an oscillator.
 3. The RF sender/receiver front-end of claim1, further comprising a terminating impedance operably coupled toinhibit reflections of a received signal.
 4. The RF sender/receiverfront-end of claim 1, wherein the RF sender/receiver front-end isintegrated in one semiconductor body.
 5. The RF sender/receiverfront-end of claim 4, wherein an antenna is arranged together with thesemiconductor body in a single chip package.
 6. An arrangement for usein an RF transceiver, comprising: a terminal operably coupled to receivean oscillator signal, at least one distribution unit configured todistribute the oscillator signal into different signal paths, two ormore mixer arrangements configured to send a transmit signal or receivea receive signal, each mixer arrangement is operably coupled in one ofthe different signal paths, each mixer arrangement comprising a mixerand an amplifier configured to amplify the oscillator signal.
 7. Thearrangement of claim 6, further comprising an oscillator coupled to theterminal.
 8. The arrangement of claim 6, wherein the amplifier can becontrollably enabled and disabled.
 9. The arrangement of claim 6,wherein: a first mixer arrangement is coupled in a first of thedifferent signal paths and is configured to transmit or receive RFsignals in a first frequency band; and a second mixer arrangement iscoupled in a second of the different signal paths and is configured totransmit or receive RF signals in a second frequency band that isdifferent than the first frequency band.
 10. The arrangement of claim 9,wherein the first frequency band is employed for near area radarlocation, and the second frequency band is employed for far area radarlocation.
 11. The arrangement of claim 9, wherein the amplifier can becontrollably enabled and disabled.